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2V sheets-sheet 1.

Patented Deo PNEUMATIG TOOL.

E. W. R. VGN BHLBR.

l (No Model.)

ATTO RNEY` Y INVENTOR WITN'ESSES z ZSheets-Sheet 2. E. W. R. VON BUHLER.

PNBUMATIG TUOI..

(No Model.)

NITE STATES PATENT GFFICE.

' 'EMIL WILHELM REINHARDT VON BHLER, OF BRLIN, GERMANY.

SPECIFICATION -forming part of Letters gPratentgNo. 510,155, datedDecember 5, 1893.

.Application ned April 1. 189,3. senti No.4ea754. (Nomura.)

To a/ZZ whom it' mety'concern: v i y Be it known that I, EMIL WILHELMRETN- HARDT voN BHLER, a subject of the King of Vrteniberg, residing atthe city of Berlin, in thejingdom of Prussia, Empire of Germany,vhaveinvented certain new `and useful Improvements in Motors Adapted forPneumatic Tools and other Purposes, ofwhich the following is aspecification.

My invention relates to pressure motors generally, but more especiallyto apparatus for operating reciprocating tools byy compressed air orother iiuid; the same being designed for commercial uses suchras stonedressing, calking, riveting, dental plugging, dac., or rock drilling orother purposes.- Y

The object of my invention is, in a pneumatic tool, to secure thenecessary capacity of the induction and educt-ion ports or passages forconducting the motive Huid to and from the cylinder, and also toregulate the velocity of the piston for a given pressure.

The distribution of actuating fluid has in pneumatic tools heretoforeinvariably been accomplished through the agency of a transverselyreciprocating valve within the piston or within the diametric limit ofthe cylinder, which valve has therefore been of restricted dimension andcorrespondingly restricted portage, and would not admit of speedregulation. Moreover, the wear and tear of the small sized valveheretofore used has been such as to render the durability of the ma-vchine imperfect.

To the ends above indicated the invention consists in a cylindric orannular distributing valve circumferentially interposed `between thepiston and the cylinder, and also in suitable means for actuatingthesaid valve by the motion of the said piston; and in order to enableothers skilled in the art to which my invention appertains to understandand use the same, I will proceed to describe the details of itsconstruction, explain its operation and subsequently point out vintheappended claims its novel characteristics.

Referring to theaccompanying drawings in which similar letters ofreference indicate corresponding partsthroughout the several views,Figure l, represents a longitudinal sectional elevation of a pneumatictool constructed according to my invention; Fig. 2, a crosssection ofFig. 1, taken on the line w, w; Fig. 3,

'a cross-section of Fig. l, taken on the line x, x; and Fig. 4, a detailview of one of the retarding springs employed on `the annular valve inFig. 1. Fig. 5, is a longitudinal sectional elevation showing a modifiedconstruction of my invention as applied to a pneumatic tool; Fig. 6, across-section of Fig. 5

ltaken on the line y, y; and Fig. 7, a crosssection of Fig. 5, taken onthe line 5,5. Fig. 8, is a partial longitudinal section showing amodification of the retarding spring applied to the valve; and Fig. 9, adetail View of the `said retarding spring detached.

In the construction shown in Figs. l to 4 inclusive, C, represents theexternal cylinder forming the body of the tool within which the movableparts are concentrated as much as possible for the purpose of promotingconvenient manipulation. E, is the tool holder or tool head which ismovable in a cavity in the lower part of the cylindric body of the toolasindicated; the said holder or head being retracted at the intervals ofthe blows by a spiral spring H or other 'suitable or well known means.B, is the reciprocating piston, the downwardly projecting shank I ofwhich abuts on the tool holder or head E, atv each descending stroke.The cylinder is double acting, `the motive fluid being supplied and`exhausted at eachfend of the cylinder.Y In

i Fig.r1,the upper end of the cylinder isclosed bya V,head F, which isretained in position by means of the screwed cap D, which also bearsa-nipple k, adapted for the attachment of a flexible supply tube. Thecap D, being hollow, provides a conduit for the introduction ofthemotive fluid to the induction passages a, b, of the mot-or cylinder.a,- bare the induction ports at the respective ends of the cylinder; c,cl, are the induction passages near the respective ends of the valve A;c', d are theexhaust passages near the respective ends at the oppositeside of the said valve A, and a', h', are the exhaust ports at therespective ends on the opposite side of the cylinder C. These severalports or passages are so arranged that when the valve A, is atl theupper end of its. stroke, as represented in the drawings, the inductionports ct, c, coincide and establish admission above the piston B,

Awhile the, exhaust ports h', cl', are closed.

IOO

The induction ports l), LZ, at such upper position of the said valve A,are `out of coincidence, while the exhaust ports c', a', coincide andestablish the exhaust beneath the piston as seen. When the valve A, isat its lower extremity of stroke, the port connections are reversed,applying pressure beneath the piston B and exhausting it. above. Thevalve A, is retarded against displacement at animproper time by thefrictional engagement of the annular split rings Zt, on the cylinder C.Motion is imparted to the valve A, by means of the transverse pin f inthe piston, projecting from the sides thereof, into longitudinal slotse, e, in the valve A. The slots e, are of such length that thereciprocation of the pin f, therein shall occur at a distance less thanthe full stroke of the piston. Thus the piston moves the valve duringthe latter part of its stroke,to reverse the distribution of pressure.The piston B, is provided with spring rings g, adapted to render itpressure tight within the cylindric valve A, and also to take up Wear.fn, represents an adj usting plug valve adapted to vary the capacity otthe lower induction passage b, for the purpose of varying the velocityof the tool.

Referring now to Figs. 5 to 9 inclusive, the cylindric valve A, isclosed at its ends. In this construction the transverse pin f, isdispensed with and the ends of the piston itself are permitted to abutor to act through an Vair cushion on the heads m, Z, of the valve A toactuate it. The arrangement of the ports in Fig. 5, is substantiallysimilarto that illustrated in Fig. 1, excepting that the inlet nipple k,is located upon the side of the cylinder C, in lieu of the end; thetiexible tubing being thereby attached at the side and admitting theprovision of a handle .I at the extremity of the tool for manipulatingit. In order to avoid theloss of momentum which would be involved by tooabrupt concussion of the piston B, on the head Z, of the valve indescending, an air cushion or other spring may be provided at p, whichis designed to check the abutment of the parts A, B, and reserve thefull force of the blow for the tool holder E. The air cushion at p, isobtained by locating the exhaust passage c in the valve a little abovethe valve head Z, so that the escape of air is checked or totallycutoff, before the piston actually abuts on Z. In lieu of sucharrangement, a spiral ring may be obviously employed in interpositionbetween the lower end of the pistou B, andthe head Z.

In Fig. 8, the modification illustrated consists in the provision of aretarding spring fr, situated in the cylinder C, having notches s,engaging with the corresponding projections f, on the valve A. Theentrance of the projections j', into the notches s, of the spring servesto retain the valve at its respective extremities of stroke until forcedout of such position by the abutment of the piston B, in the mannerhereinbefore described.

The operation of the invention consists as follows: The piston B, beingat its upper extremity of stroke the valve A is also raised, and theinduction ports a, c, open above the piston; the exhaust ports d', bbeing closed. The induction ports Z), CZ, are closed and the exhaustports a', c', open beneath the piston'. The piston then descendsdelivering a sharp blow upon the tool before the'valve A, which iscarried with it has closed at a., c. lVith the termination ofthedescending stroke of the piston B, the downward stroke of the valve A,isalso completed, reversing the distribution of pressure, driving thepiston upward. In Fig. 5, before the piston B or any connected partthereof has come into contact with the valve A, to move it, theinterposed aircushion at p, serves to start the valve A on its downwardstroke so that the latter will have 'terminated its movement before orat the time the piston B actually abuts thereon, if at all. The onlyabrupt concussion arresting or tending to arrest the descending movementof the piston B, thereby occurs at its impact on the tool holder or headE, concentrating the full effective force of momentum upon the tool. Inapparatus used heretofore for distributing motive pressure to thereciprocating piston of a pneumatic tool, in which the distributingvalve has been located diametrically within the piston or cylinder head,various difficulties have presented themselves, based particularly uponthe fact that the area of the conduits for thc supply of compressed airdepended upon the diameter of the piston or that of the cylindric bodyof the tool, and that it was not admissible to have the same exceed theone-fortieth part of the area of such piston, while the distributingvalve being of a very limited dimension and stroke, it has moreover beennecessary to give the same cross sections to the admission and thedischarge ports, which in other respects is undesirable and unsuitable.The small distance traveled by the slide valve, on the other hand,determined the cross sections of the supply and discharge ports, whichhad to be made not to exceed one-fifth of the travel of said slidevalve, in order to prevent leakage along the valve seat from the supplyports to the discharge ports. ciency of tools operated by compressed airwas exceedingly limited, and could not be increased as circumstances andthe particular uses to which the tool had to be put might require. Theefficiency of the tool soon suffered from the fact that owing to theshort distan ce between the admission and discharge ports as Well asbetween the ports above and below the piston, wearing of the slide valveoccurred quickly causing back pressure. Moreover the piston which inpractice moves at the rate of about six thousand down strokes per minutecould not be regulated by varying the admission capacity of the portsowing 1 to their concentrated arrangement and inaccessible position.

By means of my invention I acquirelarger Consequently the effl-` bearingsurfaces for the valve, and corresponding durability and strength of thesame to resist wear and tear, and I also acquire acv cess to the portsfor regulating the relative capacity thereof, and the velocity of thepiston according to the requirements ofthe work.

The normal areas of the induction and discharge ports may be as much asdesired according to my present construction, and the 1) area of thelower induction port b, for retracting the piston may be varied by meansof the screw plug o, indicated. According to the 1 regulation of theport b, the velocity of the piston or intervals occupied duringretraction between its blows upon the tool head may be increased ordecreased at will. The greatest rapidity of movement is acquired bymaking Y the areas of the admission ports above .and

air cushions at the u p-stroke as well as at the down-stroke, in themanner described, and it is to be observed moreover that air cushionsare or may be formed above and beneath the ,yalve A, between the sameand the respective @nds of the cylinder C, in the construction shown inFig. 5, or in the spaces '[,in the construction shown in Fig. l. Havingthus fully described my invention, ,what I claim, and desire to secureby Letters `Patent, is-

1. In a motor, the combination with a cylinder and a reciprocatingpiston therein, of a cylindric distributing valve circumferenytiallyinterposed and longitudinally movable between the piston and thecylinder, and i through an opening in the piston, substantially asdescribed. l

'2. The combination in a motor, with a cylinder and a reciprocatingpiston therein, of a longitudinally movable cylindrical distributingvalve circumferentially interposed between said piston and saidcylinder, induction and eduction ports in the cylinder, andcorresponding induction and eduction ports in the valve, the same beinglocated so as to operate in the manner described, and means for varyingthe area of the lower induction port.

3. In a motor, the combination with a cylinder and a reciprocatingpiston therein, of a longitudinally movable cylindrical distributingvalve circu mferentially interposed between the said piston and the saidcylinder, and a spring interposed between said valve and said cylinder,and means for interlocking the said spring with the valve and adapted toretard the valve against premature displacement by the friction of thepiston thereon, substantially as described.

4. In a pneumatic tool the combination with a tool holder, a pressurecylinder, and a reciprocating piston therein, of a reciprocating annularvalve interposed between the piston and the cylinder, and a removablehead provided at one end of the cylinder containing passages therein forthe conduction of the motive fluid, substantially as described.

In witness-whereof I have hereunto set my hand in presence of twowitnesses.

EMIL WILHELM REINHARD'I VON BHLER.

Witnesses:

CHR. Faison, A. R. DUNNE.

